Few dedicated attempts at comparing the monitoring performance of lower and higher plants have been carried out so far. As a contribution to such an issue, this paper looks into the relative magnitude of elemental signals from epiphytic lichens (Parmelia spp.) and olive tree (Olea europaea Linn.) bark, determined by INAA. A representative set of 12 elements - As, Ba, Br, Ca, Cl, K, Mg, Mn, Na, Sr, V, Zn - was used for an ab initio comparison between raw data and Rb-normalized data, using distribution-free statistics. Correlation analysis shows an overall improvement in the degree of association between bark and lichen signals when proceeding from raw data to relative enrichment. Apart from Cl, no element is enriched in lichens to a higher extent than in bark. Sign tests are quite conclusive: bark factors are either statistically greater than or equal to lichens'. These findings prompt a word of caution when dealing with biological monitoring data, without accounting for soil, rock or litter inputs into the biomonitors' elemental pools.
Mass and elemental concentrations in PM10 and PM2.5 — airborne particulate matter with an aerodynamic diameter below 10 μm and 2.5 μm, respectively — have been evaluated in
mainland Portugal since 1993. The data herein refer to areas generally impacted by emissions from electrical power plants,
either coal- or oil-fired, which are mostly large, state-of-the-art facilities. Background areas have been sampled as well,
and results from one of them are given for comparison. Through the country, lead levels are well below the European enacted
values, particularly since unleaded fuels became mandatory in the late 1990s. Nickel appears especially concentrated in PM2.5 and, apart from extreme cases (rural sites, coal-fired plants), its levels are not significantly different from place to
place. Highest values for arsenic and mercury have been found in the vicinity of the coal-fired plants. Cadmium data, if only
available for metropolitan Lisbon, seems to confirm the trend for anthropogenic elements appearing mainly in fine particulates.
Chemical elements were determined in epiphytic lichens from Terceira and Santa Maria islands (Azores, Portugal), by k0-standardized, instrumental neutron activation analysis. Abundance ranges were generally below those in mainland Portugal,
except for Br (Terceira), Cl (Santa Maria), Na (Santa Maria), and Se (both islands). Elemental (averaged) contents of As,
Br, Cl, Co, Cr, Mg, Na, Se, Hg and Zn were significantly different between the islands. Anthropogenic influence was discernible
in Terceira if not in Santa Maria, where only crustal and marine sources are apparent.
Here we present a new proof of Blatter's result: a normed space is complete if every bounded closed convex subset has an element of minimum norm. We also present geometrical conditions for the existence of minimum-norm elements in bounded closed convex sets. Also, we characterize reflexivity in the class of Banach spaces by means of contraction functions. Furthermore, we study what happens if we remove the completeness hypothesis.
The replicate sample instrumental neutron activation method was optimized and used for the determination of selenium in foodstuffs.
The method was reliable, yielding accurate results. Lower detections limits were obtained after each successive irradiation.
Different irradiation conditions were used depending on the type of sample. For samples with higher selenium contents (meat,
fish, eggs), the measured selenium in the first replicate is in all cases larger than the detection limit, but a better accuracy
was obtained with a larger number of replicates (2–3 replicates). For samples with extremely low selenium contents (vegetable
samples), at least seven replicates were necessary to obtain a concentration value two times larger than the detection limit.
Selenium daily intake was determined for two small groups of the Portuguese population, based on the analysis of duplicate
diet portions. The total amount of food ingested during a day was collected for 18 workers of the Technological and Nuclear
Institute (ITN-Sacavém) and for 6 females of Reguengos de Monsaraz, a small town in the south-eastern hinterland. The average
selenium daily intake was 43 ± 20 and 32 ± 13 μg per person, respectively, both lower than the Recommended Dietary Allowance
(RDA) of 55 μg day−1. Selenium in diet samples was determined by replicate sample neutron activation analysis (RSINAA). The method was considered
accurate for the selenium determination.
An extensive investigation of elemental levels in cereals and their cultivation soils has been going on across the main production
areas of mainland Portugal, with a view to an eventual biofortification of major cultivars through agronomic practices. Cereals
are an obvious choice as primary vehicles for food-supplementation programs, especially in countries where they definitely
weigh in the dietary intake (like Portugal), and regions whose geographical and/or pedological features may account for nutrient
deficiencies in typical diets. Mature rye plants (Secale cereale L.; roots and grains) and local soils were collected in the summer of 2009 from two regions of northern Portugal, and put
through k0-standardized, instrumental neutron activation analysis (k0-INAA). Overall, the results (elemental concentrations, enrichment factors, transfer coefficients) seem to confirm an efficient
uptake of elements from soil and their translocation to the aerial parts of the plants, notably to the ones that really matter
in human nutrition (grains).
Authors:B. Vieira, M. Freitas, A. Rodrigues, A. Pacheco, and P. Soares
Within an extensive survey of prevalent lower and higher plants in the Azores’ islands, with a view to their monitoring potential
for airborne elements at ground level, and then to an eventual use in evaluation routines for the archipelago, epiphytic lichens
were collected from Cryptomeria japonica (Japanese cedar) trunks all across Terceira and Santa Maria islands. After suitable procedures, thalli samples were put through
instrumental neutron activation analysis (INAA; k0-variant) for elemental concentrations. Providing an overall view of micro-and trace-element levels in representative foliose-and
fruticose-type species, the data of high-level elements agree generally well for genera with distinct species, with a relatively
low interspecies variability. Principal-component analysis of the whole set of results discriminates clearly between two morphological
factors, corresponding to foliose and fruticose species, and likely among four major origins of elemental inputs: soil/dust
(two factors), sea spray and an antimony-related source. All things considered, and accounting for its availability and ubiquity,
Parmotrema bangii seems an adequate choice for further lichen-based, biomonitoring campaigns in the Azores archipelago.
Authors:A. Pacheco, M. Freitas, M. Baptista, M. Vasconcelos, and J. Cabral
This study deals with the influence of the exposure conditions on biological uptake, by looking into concentrations of Ni
and V in lichen thalli and tree bark after continuous and discontinuous field trials at littoral sites impacted by anthropogenic
emissions. Biomonitors were assessed by k0-INAA and AAS. Correlations at Sines are more apparent than at Viana or Lisboa. When data from all sites are pooled, V shows
correlations for practically every situation while Ni shows none, which may indicate a dissimilar uptake mechanism for each
element. At Sines, V/Ni ratios reach values that comply with emissions from oil-related industries.